Variable pitch propeller

ABSTRACT

A propeller having differently dimensioned integrally connected blades positioned on a drive shaft in nonsymmetrical relationship. As the blades rotate with respect to the drive shaft, one of blades changes its blade angle of attack while the other remains at a constant blade angle of attack.

United States Patent [72] inventor Clifton W. Hall Rte. 17, Knoxville, Tenn. 37921 [21] Appl. No. 757,670 [22] Filed Sept. 5, 1968 [45] Patented Apr. 20, 1971 [54] VARIABLE PITCH PROPELLER 8 Claims, 15 Drawing Figs.

[52] US. Cl 416/131, 416/203 [51] int. Cl B63h 3/00 [50] Field of Search 170/160.1, 160.27,166,170,416/159,18,19(Cursory),203, 131,141,202, 102

[56] References Cited UNITED STATES PATENTS 24,508 6/1859 Vergne 170/170 Primary Examiner-Everette A. Powell, Jr. Attorneys-Clarence A. OBrien and Harvey B. Jacobson ABSTRACT: A propeller having differently dimensioned integrally connected blades positioned on a drive shaft in nonsymmetrical relationship. As the blades rotate with respect to the drive shaft, one of blades changes its blade angle of attack while the other remains at a constant blade angle of attack.

Thrus+ PATENIEU APR2'0 l97l SHEET 1 OF 3 o lnpu'l' Power Clifton W. Hall INVENTOR.

BY W

PATENTEDAPRZOIQH 3575530 SHEETEUF 3 Clifton W Hall PATENTED APR 20 1971 SHEET 3 OF 3 C/if fan WHa/l 'IWENT R.

VARIABLE lPll'lClli FROPELILER The present invention relates to propellers and more particularly to an automatically adjustable blade assembly.

Propeller assemblies pivotally mounted on a rotating shaft have been proposed to compensate for and diminish the resistance of a propeller whenever a force is applied to change the direction of its axis of rotation. Such propellers have been somewhat successful in automatically opposing or overcoming various factors otherwise tending to cause dynamic unbalance and dynamic thrust unbalance. The blades employed in previous compensating propellers have been similarly dimensioned and disposed in symmetrical spaced relation about the axis of the rotating shaft.

A basic concept of the present invention includes the integral connection of two dissimilar blades by a link permitting pivotal adjustment of the blade means so as to increase the efficiency of the propeller. The present invention also contemplates the addition of a spiral groove formed in the thrust surface of the propeller embodiments in order to diminish turbulence of the fluid immediately adjacent the propeller blades.

One of the principles underlying the present invention resides in the disproportionality of the thrust surfaces of the blade means. Thus, forces exerted upon differently dimensioned blade members under aerodynamic or marine conditions will vary and cause pivotal adjustment of the blade means until a point of dynamic balance is reached. This finally assumed position tends to avoid dynamic unbalance and dynamic thrust unbalance of the propeller otherwise produced. The same operating principles and blade design considerations may be used in a turbine rotor assembly or a fluid coupling assembly. Further, the present invention may be utilized in any machine where fluid resistance across a propeller changes as for example boat propellers, pumps, transmissions, vacuum cleaners, helicopters, wind tunnels, automobile fan blades, and the like.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout, and in which:

FIG. I is a front elevational view illustrating one embodiment of the present invention.

FIG. 2 is a side elevational view of the propeller shown in FIG. i.

FIG. 3 is a partial longitudinal sectional view taken along a plane passing through section line 3-3 of FIG. ll.

FIG. 4 is a partial transverse sectional view taken along a plane passing through section line M of FIG. 3.

FIG. 5 is a cross-sectional view illustrating the contour of a spiral groove formed in the thrust surface of the propeller shown in FIG. ll.

FIG. 6 is a graphical representation of test results comparing the performance of an automatically adjustable propeller assembly such as that illustrated in FIG. 1 with that of a conventional blade propeller.

FIG. 7 illustrates a side elevational view of the second embodiment of the present invention.

FIG. d is a transverse sectional view taken along a plane passing through section line M of FIG. 7.

FIG. El is a front elevational view of the third embodiment of the present invention.

FIG. i0 is a side elevational view of the third embodiment of the present invention.

FlG. I1 is a transverse sectional view taken along a plane passing through section line 11-11 of FIG. 10.

FIG. 12 is a partial front elevational view of a turbine rotor installation for blade assemblies constructed in accordance with the present invention.

FIG. 13 is a longitudinal sectional view through a fluid torque transmitter installation for the present invention.

F IO. M is a transverse sectional view taken through a plane indicated by section line i l-M in FIG. 113.

FIG. 15 is a side section view showing the impeller assembly associated with the installation of FIGS. l3 and 14.

At the outset it must be emphasized that the following species have a common characteristic. In each species, a pair of blades are interconnected in nondiametrical relationship. As the blades rotate with respect to the drive shaft, one of the blades changes its blade angle of attack while the other remains at a constant blade angle of attack.

Referring to the drawings and initially to FIGS. 1-5, a first embodiment of the present invention is denoted by reference numeral 10 and is seen to include a shaft section 12 extending forwardly to a nose cone portion M. An intermediate length of the shaft includes a spherical surface formation 16 having a center of curvature lying on the axis of shaft 12. Converging edged shoulders 18 and 20 areformed between the nose cone portion 14 and shaft 12 having vertices 21 spaced 180 apart. An annular hub 22 is concentrically positioned around the formation 16, and is caused to pivot forwardly and rearwardly with respect to the axis of shaft 12 by means of pivot pin 23 which extends diametrically through the fonnation 16 and is received within aligned bores 25 formed within hub 22. Thus, pin 23 establishes a pivot axis for hub 22 intersecting the rotational axis of shaft 12 at the center of curvature of formation 16, the pivot axis also being aligned between the vertices 21 of shoulders l8 and 20.

FIGS. l and 2 clearly illustrate the blade configuration of the first embodiment of the present invention wherein a first blade 24 is attached to hub 22 by means of a connecting portion 26 through which the blade axis extends. A second blade 28 is also attached to hub 22 by means of a connecting portion 30 which its blade axis extends. The second blade is dimensionally smaller than blade 24 and angularly spaced from one another by an amount ranging between and 180. In the illustrated embodiment, the blades are spaced apart by between the respective blade axes. The blades are peripherally contoured in accordance with conventional blade design principles. In order to decrease the amount of turbulence resulting from propeller action in a fluid, a spiral groove is formed on the thrust face of both blades 24 and 28 as denoted by reference numeral 36 and 36 in FIG. 2. FIG. 5 shows in cross section the groove formation.

Referring to FIG. 3, a rotating power shaft 38 is received within a bore axially formed within the propeller shaft 12. The input shaft 38 is secured to the propeller assembly by means of setscrews d0 received within propeller shaft 12. The propeller blade assembly 10 may accordingly be rotated underwater in a marine installation for propulsion purposes by way of example. Under given conditions, the hub 22 and the blades will pivot to a predetermined pitch position on the shaft 12 between limits established by the shoulders 18 and 20. Forward and rearward pivotal displacement from a central position by amounts 91 and 62 is accommodated as depicted in FIG. 2. In a test model of the propeller assembly a value of 22 was selected for GI and 62. In operation, as the blades pivot, the smaller blade 28 maintains a constant blade angle of attack while the blade angle of attack of the larger blade 24 vanes.

FIG. 6 graphically represents test result data comparing the propeller structure of the aforementioned first embodiment with that of a conventional stationary pitch propeller. The graph shown in FIG. 6 is a plot of thrust as a function of shaft input power. The test results were obtained with a first embodiment propeller, excluding the spiral on the thrust face 36, placed in a closed fluid circuit through which water was circulated by the propeller assembly. In order to obtain the thrust-input power characteristics of the tested propellers, a test setup was arranged in a conduit forming part of the fluid circuit. A valve member in the circuit was first manipulated to an open position permitting free circulation representing a noload condition upon the propeller. Then, the valve was manipulated to a half-opened position to load the propeller assembly by restricting flow through the circuit. All the curves were plotted up to a maximum thrust obtainable, by

measuring the power drawn by an electric motor driving the propeller assembly and metering flow through the circuit by static and dynamic pressure sensors. The lowermost curve 42 represents a no-load condition for a stationary pitch, conventional propeller. The curve denoted by reference numeral 44 represents the no-load characteristics of the propeller of the present invention. As will be observed, the present propeller exhibits greater thrust at any particular input power over the entire range plotted. The curve denoted by 46 represents the characteristics of a stationary pitch propeller of the conventional type under load. The uppermost plotted curve denoted by 48 represents the load characteristics of the present propeller. Hereagain it will be observed that the present propeller structure exhibits greater thrust over the entire range of input power.

FIGS. 7 and 8 illustrate a second embodiment of the present invention and is seen to include a propeller assembly generally denoted by reference numeral 50. This second propeller embodiment includes a shaft section 52 extending forwardly to a nose cone portion 54. An intermediately disposed spherical shell formation 56 is coaxially formed between shaft 52 and nose cone portion 54. Further, the formation 56 has a center of curvature coincident with the axis of shaft 52. Inwardly tapering shoulders 58 and 60 join nose cone portion 54 and shaft 52 to the spherical formation 56 to limit pivotal motion of an arcuate hub section 62 mounted upon the formation 56, in a manner similar to that of the first embodiment. Blade members 64 and 66 are integrally connected to a first hub portion 62. The blade members are contoured in a conventional manner and are displaced from one another by 120. A second hub section 62' is disposed in circumferentially spaced relation to the first mentioned hub portion 62 and mounts a third blade member 68 which is identical to members 64 and 66. Circumferential spaces 70 and 72 separate hub portions 62 and 62, thereby permitting pivotal displacement of hub section 62 with respect to hub section 62 as hereinafter explained.

A first pin 74 is splined at one end thereof to hub section 62 and passes through a journal bore 76 in formation 56. The opposite end of pin 74 is joumaled in bore 78. The bores 76 and 78 are formed within formation 56in a manner permitting rotation of pin 74 with respect to the formation 56. A first bevel gear 82 is mounted upon pin 74 adjacent aperture 78. A second pin 84 is splined to hub section 62' as indicated by 86 and passes radially inwardly through a radial bore 87 for attachment at an opposite end to a second bevel gear 88 meshing with the first mentioned bevel gear 82.

In operation of the second propeller embodiment 50, pivotal displacement of the hub section 62 with respect to shaft 52 causes rotation of associated bevel gear 82, this motion being transmitted to bevel gear 88. Because bevel gear 88 is meshed with bevel gear 82, this pivotal displacement is linked to hub section 62' thereby causing simultaneous pivotal displacement of all blade members. Blades 64 and 66 are fixedly mounted on hub section 62 and while they are of the same dimension and contour as the third blade 68, they form an equivalent blade assembly which is different in effective dimension and effective pressure center than blade 68. As the blades pivot, the angle of attack of linked blades 64 and 66 varies while the angle of attack of the smaller blade 68 remains constant.

A third propeller embodiment of the present invention is represented in FIGS. 9--11 and is denoted by reference numeral 92. Referring in particular to FIG. 10, the third embodiment includes a shaft portion 94 extending forwardly to a nose cone portion 96. A hollow hub 98 fixedly interconnects nose cone portion 96 and shaft portion 94. Pivotally mounted within this hub is a first blade assembly generally denoted by reference numeral 100 and a second blade assembly denoted by 102. The first blade assembly 100 includes a stem portion 104 as shown in FIG. 11 rotatably received within journal bore 105 of hub 98. The stem extends inwardly to an arcuate linking portion 106 connected to a stem portion 107 joumaled by hub 98 about a pivot axis extending through bore offset from the rotational axis of the shaft 94. An elongated blade member 108 is connected to stem 104. A second stem portion 110 is attached to the arcuate linking portion 106 and extends outwardly through an elongated slot 112 formed within hub 98. The external appearance of slot 112 is seen in FIG. 10. A foreshortened blade member 114 is connected to the outward end of stem 110 so that stems 104 and 110 are substantially perpendicular to one another.

The second blade assembly 102 is identical to that of 100 and is pivotally mounted in hub 98 about a parallel pivot axis offset from the rotational axis of shaft 94 on the opposite side. For purposes of convenience, component portions of the second blade assembly 102 have been numbered in the same manner as the components of the first blade assembly 100 except that the numbering of the second blade assembly 102 is primed.

In operation of the propeller assembly 92, rotation of shaft 94 causes rotation of blade members 108 and 108 about its rotational axis while forward or rearward pivotal displacement of the blade members occurs with respect to the parallel spaced pivotal axes aforementioned until the blade members assume predetermined pitch positions under given conditions. When the blades rotate, the blade angle of attack of each small blade 114,114 remains constant while the blade angle of attack of the larger blades 108,108 varies.

Referring to FIG. 12, a turbine rotor assembly 116 is shown and is seen to include a plurality of peripherally mounted vane assemblies 210 which are similar to the first mentioned propeller embodiment 10 shown in FIG. 1. The pivot pin 223 of each vane assembly is radially disposed and the blade members 224 and 228 pivot thereabout to predetermined pitch positions. The present embodiment is contemplated as being useful in efficiently converting the rotor assembly kinetic energy of fluid into rotational energy of a turbine. When the vane assembly rotates, the blade angle of attack of member 224 remains constant while the blade angle of attack of member 228 varies.

FIGS. 13 and 14 illustrate an application of the present invention in a fluid torque transmitter 118 having a housing 120. A conventional driven turbine blade assembly 126 is enclosed within the housing which receives fluid energy through a toroidal flow chamber 122. The fluid transmitter also includes an impeller assembly 132 mounted upon an input or drive shaft 134 joumaled in sealed relation within housing by bearing assemblies 136 and 138, the latter being received within a bored aperture in turbine rotor hub 126. It is contemplated that any of the aforementioned embodiments 10, 50 or 92 may be utilized as the impeller assembly except that pivotal displacement is restricted to movement in one direction from a central position. Thus, the shaft 134 mounts a formation 140 having offset portions 142 and 144 as shown in FIG. 15. As will be observed from FIG. 15, rearward pivotal displacement of the blade assembly is prevented when hub 322 is parallel to hub portions 142 and 144. A pin 146 is received within diametrically aligned apertures formed in hub 322 and the hub portion 144 thereby establishing a pivotal axis for the blade assembly.

In operation of the fluid transmitter 118, the rotating impeller assembly 132 assumes a predetermined pitch position under a given load condition to cause toroidal flow of fluid through the blades 124 of the turbine rotor and the guide channels 148 of the housing for transmission of rotational torque to the turbine rotor shaft 128. The blades 324 and 328 exhibit blade attack characteristics as discussed previously in connection with FIGS. 1-4.

In each of the foregoing embodiments of the invention, the pivoted hub or hub section moves to a predetermined pitch position determined by the pressure exerted on the thrust faces of the blade or blades, carried by the hub or hub section, by the fluid medium as well as the centrifugal forces acting on the blades during rotation. Further, since there are at least two blades having either dimensionally different contours or thrust face areas, and such blades have pressure centers radially spaced from the rotational axis on opposite sides, the resulting differences in thrusts and/or moment arms will affect the pitch position assumed because the blades are mechanically interconnected. Thus, the relative blade dimensions and contours are selected in order to cause pivotal movement of the blades to pitch positions calculated to be ideal for given fluid conditions under which the propeller, vane or impeller assembly is to operate. The asymmetrical arrangement of the blades on the hub provides for greater design selection so as to make possible higher efficiencies under varying fluid conditions contemplated during operation of the blade assembly.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the an, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

1 claim:

ll. A bladed rotor device comprising a first blade, a second blade having a substantially different blade area than the first blade and positioned in nondiametn'cal relation thereto, a hub link connecting the blades, support means connected to the link for enabling pivotal motion of the linked blades about the axis of the support means, the pivotal motion causing the blade angle of attack of one blade to vary while the blade angle of other blade remains constant.

2. The structure of claim 1 wherein the link is a hub portion and further wherein a drive shaft axially passes through the hub portion, the support means comprises a pivot pin diametrically extending through the shaft and the hub portion, the shaft having an arcuate surface with a center of curvature coinciding with the pin, the shaft having shoulder surfaces for limiting movement of the hub portion.

3. The structure of claim 1 together with a hub having first and second apertures therein, a third oversized aperture formed in perpendicular relation to the first and second apertures, the support means including separated pin elements journaled in the first and second apertures, an arcuate strip connecting the elements to serve as the link, the first blade being outwardly attached to one of the pin elements so that it can execute the varying angles of attack, and an element passing through the third aperture for connecting the second blade to the link for allowing the blade to maintain a constant angle of attack.

4. The structure of claim 3 wherein a complemental set of blades are similarly connected with a second link within the housing for executing identical rotational characteristics, the resulting structure being symmetrical.

5. The structure of claim ll wherein the first blade includes two integrally connected blade elements spaced from each other, said second blade being a single blade element positioned [20 from both blade elements of said first blade, and wherein the link means include gear members for causing simultaneous pivotal movement of said first and second blades.

6. The device set forth in claim 1 together with spiral grooves formed in thrust surfaces of the blades for reducing thrust imbalance.

7. in a turbine rotor, a vane assembly comprising a plurality of bladed members spaced peripherally around the rotor, each said bladed member comprising a first blade portion, a second blade portion substantially different in dimension and angularly oriented from said first blade portion, a rocking hub portion on which said blade portions are connected, a shaft pivotally mounting the hub portion so that each bladed member executes limited movement relative to said shaft whereby in each bladed member the first blade portion executes rotation with a constant blade angle of attack and the second blade portion executes rotation with a varying blade angle of attack.

8. In a fluid torque transmitting device an input impeller comprising an input shaft, a bladed rotor including a blade, a second blade substantially different in dimension and obliquely oriented with respect to said first blade, a rocking hub on which said blades are mounted, pin means pivotally mounting said hub to the shaft enabling the first blade to execute rotation with a constant blade angle of attack while the second blade executes rotation only with a varying blade angle of attack. 

1. A bladed rotor device comprising a first blade, a second blade having a substantially different blade area than the first blade and positioned in nondiametrical relation thereto, a hub link connecting the blades, support means connected to the link for enabling pivotal motion of the linked blades about the axis of the support means, the pivotal motion causing the blade angle of attack of one blade to vary while the blade angle of other blade remains constant.
 2. The structure of claim 1 wherein the link is a hub portion and further wherein a drive shaft axially passes through the hub portion, the support means comprises a pivot pin diametrically extending through the shaft and the hub portion, the shaft having an arcuate surface with a center of curvature coinciding with the pin, the shaft having shoulder surfaces for limiting movement of the hub portion.
 3. The structure of claim 1 together with a hub having first and second apertures therein, a third oversized aperture formed in perpendicular relation to the first and second apertures, the support means including separated pin elements journaled in the first and second apertures, an arcuate strip connecting the elements to serve as the link, the first blade being outwardly attached to one of the pin elements so that it can execute the varying angles of attack, and an element passing through the third aperture for connecting the second blade to the link for allowing the blade to maintain a constant angle of attack.
 4. The structure of claim 3 wherein a complemental set of blades are similarly connected with a second link within the housing for executing identical rotational characteristics, the resulting structure being symmetrical.
 5. The structure of claim 1 wherein the first blade includes two integrally connected blade elements spaced 120* from each other, said second blade being a single blade element positioned 120* from both blade elements of said first blade, and wherein the link means include gear members for causing simultaneous pivotal movement of said first and second blades.
 6. The device set forth in claim 1 together with spiral grooves formed in thrust surfaces of the blades for reducing thrust imbalance.
 7. In a turbine rotor, a vane assembly comprising a plurality of bladed members spaced peripherally around the rotor, each said bladed member comprising a first blade portion, a second blade portion substantially different in dimension and angularly oriented from said first blade portion, a rocking hub portion on which said blade portions are connected, a shaft pivotally mounting the hub portion so that each bladed member executes limited movement relative to said shaft whereby in each bladed member the first blade portion executes rotation with a constant blade angle of attack and the second blade portion executes rotation with a varying blade angle of attack.
 8. In a fluid torque transmitting device an input impeller comprising an input shaft, a bladed rotor including a blade, a second blade substantially different in dimension and obliquely oriented with respect to said first blade, a rocking hub on which said blades are mounted, pin means pivotally mounting said hub to the shaft enabling the first blade to execute rotation with a constant blade angle of attack while the second blade executes rotation only with a varying blade angle of attack. 